The present invention in general concerns improved surge control apparatus and method, and more particularly concerns improved method and apparatus for providing surge control for easily damaged products being conveyed between two workstations.
Due to numerous considerations, it is desirable to establish production lines which run smoothly, and in general, without interruption. However, circumstances often cause undesired or unexpected variations in the operating speed of different components comprising a production line. In fact, various components may from time-to-time experience a total failure, i.e., stoppage, for either a relatively temporary period of time or for a more prolonged period of time.
Broadly speaking, the concept of surge control has heretofore been put forth, for example generally whereby the output of a relatively upstream production component is temporarily accumulated and subsequently fed to a downstream production line component. Such accumulation occurs primarily because the operating speed of the relatively upstream component overtakes that of the relatively downstream machine or workstation.
Various accumulators have been provided for use with a production line having a plurality of workstations or production areas. The following are examples of such accumulators:
______________________________________ U.S. Pat. No. INVENTOR(S) DATE ISSUED ______________________________________ 2,014,458 Winkley Sept. 17, 1935 3,016,780 Mosen Jan. 16, 1962 3,178,008 Solet Apr. 13, 1965 3,470,996 Lee et al. Oct. 7, 1969 3,499,555 Wahle Mar. 10, 1970 4,018,325 Rejsa Apr. 19, 1977 4,273,234 Bourgeois June 16, 1981 4,499,987 Long Feb. 19, 1985 4,560,057 Applegate et al. Dec. 24, 1985 ______________________________________
One feature common to many prior art accumulators is the concept of a vertically-oriented conveyor or escalator-type mechanism, with plural, spaced flights thereon for the storage or accumulation of products between adjacent of such flights. Those of ordinary skill in the art will appreciate that indexing of such vertical mechanism in alternate directions results in either removal or return of products relative a conveyor belt with which the mechanism is associated.
Various differences in the foregoing exemplary accumulators may exist in the particular methodology or apparatus for handling the products to be accumulated. For example, Long (U.S. Pat. No. 4,499,987) generally operates a stop in association with incremental movement of an array of fingers to clear a slug of cartons, until one or more detectors indicate that there is no further need for accumulation of cartons by the device 10. A second detector is used for activating a stop whenever a space for insertion of such stop is detected between cartons passing by on a delivery belt. As further example, Applegate et al. (U.S. Pat. No. 4,560,057) uses a movable platform 50, or a diverting belt 62 or 132 for directing articles or packets from a main conveyor either into an empty compartment of a reservoir or into a secondary conveyor for subsequent transfer to or from a reservoir. A laterally moving plunger 52 is used in conjunction with the movable platform 50 for securing packets generally upside-down in an open or empty compartment 40a of reservoir 14. Without side plunger 52, the packets would fall back downward upon retraction of movable plunger 50. A second movable platform 56 is used during unloading of packets.
In general, if products on a production line being subjected to surge control are substantially durable and rigid, then their precise handling and treatment may not be as critical as in the case of less durable or less rigid products. As the products involved become less rigid and more fragile, a point is reached where use of prior art accumulator systems can result in damage and even literal destruction of the handled products.
One example of products which are subject to damage by either crushing or tearing are paper packages, such as 250 ml. size packages, as produced by Tetra Pak, Combibloc, or International Paper, Inc. Such packages are presently popular in such size, and others for the marketing of drink products, such as juices, and other beverages. The manufacture of such products typically may involve aseptic conditions, thus resulting in a particularized need for an accumulator capable of successfully handling such packages. Also, such packages generally have relatively sharp corners and edges, further contributing to handling difficulties.
Moreover, the need for a highly dependable, relatively large capacity accumulator, is particularly acute in connection with aseptic paper packages. For example, the paper used in a forming and/or filler machine for such types of products may be sterilized, such as by passing same of a heated bath of hydrogen peroxide. If such machine or production is stopped, the paper (which is generally coming from a large roll) may soften and possibly break upon restart. Also, a relatively lengthy (approximately 1 hour) resterilization process may be needed in the event problems occur during a stoppage of such production area. Thus, for such reasons, and due to required efficiencies of running a profitable operation, the filler machinery must operate on a more or less continuous basis, thus virtually requiring dependable, high volume surge control despite the added problem of the ready damage potential (through crushing or tearing) of the packages involved.
For numerous reasons, accumulator operations through manual intervention is not a viable alternative. For example, human handling of such particular products may itself result in accidental product damage (e.g., crushing) such as through storage in stacked layers, or through hurried handling. Moreover, intermittent human intervention can result in lack of necessary attention to other production line activities, and hurried, time-pressure activities of workers in and around production lines can (based on all circumstances of a given situation) create a significant risk of injury to the workers.